[Stoves] Bangladesh TLUD (was Re: No subsidies in TLUD char peoduction
lh cheng
lhkind at gmail.com
Sat Dec 9 20:46:08 CST 2017
Yes, you are right, Mr Albi, my present rocket stove have preheated
secondary air supply, and third air. the secondary air holes is much less
needed comparing TLUD stove, since much of it comes from under and through
the red hot charcoal, ( so, ordinary rocket stove naturally have some very
hot "secondary air" already). it burns everything into red/blue flame and
white fine ashes, totally smokeless.
2017-12-09 15:32 GMT+08:00 Todd Albi <todd.r.albi at gmail.com>:
> Ron:
>
> Not quite correct. Secondary combustion* is possible* with a rocket
> stove. Our Survivor Rocket stove launched 5 years ago introduced preheated
> ventilation ductwork at launch. In fact we only offer a primary &
> secondary combustion design rocket stove. Thats why our stove incorporates
> 360 degree ventilation through base of stove, tied to ventilation ductwork
> behind combustion chamber walls. The double insulated walls allow
> preheated air to travel behind firebox and mix at chimney base, before
> exiting cooktop. Others have also now added preheated channels and
> secondary gasification to rocket stoves. It is not an inclusive to TLUD
> designs and can be adapted to any stove firebox.
>
>
>
> SilverFire Rocket stove on left & Hunter Chimney TLUD stove on right.
>
> Todd Albi, SilverFire
>
> On Fri, Dec 8, 2017 at 8:52 PM, Ronal W. Larson <rongretlarson at comcast.net
> > wrote:
>
>> Paul:
>>
>> Yes on your item #1. My first response forgot about preheating secondary
>> air - which is why I quickly added this point; heating secondary air is a
>> big fuel conservation advantage. Generally not possible with rocket stoves
>> - or even charcoal cookers. If not used for heating secondary air, that
>> energy would have been just another loss mechanism.
>>
>> Yes also on your #2. I suspected their problem with a concrete inner
>> cylinder was related to the secondary holes.
>>
>> But I think (not mentioned earlier) that there may be satisfactory ways
>> to use only a single concrete cylinder and still get preheating of the
>> secondary air. I’m thinking of some vertical piping or tubing - maybe in
>> the concrete. It is not obvious that two cylinders must be used. Which is
>> I guess your point.
>>
>> Re #3, if meant for me - I can probably find a way to get coconut
>> husks/shells from some local restaurants - but better to ask others than
>> myself. I am trying these days to defend biochar against other CDR
>> approaches on 3 or 4 other internet lists . So not much time left for
>> stoves - or experimenting with char in ground or elsewhere.
>> Tremendous ignorance remains about biochar; the very positive Bangladesh
>> soil experience will be very helpful in defending biochar, however
>> produced. And, of course, in advancing TLUD technology. I’m writing about
>> this elsewhere right now.
>>
>> Ron
>>
>>
>> On Dec 7, 2017, at 6:51 AM, Paul Anderson <psanders at ilstu.edu> wrote:
>>
>> Ron,
>>
>> About the concrete inner (fuel) cylinder. Hard to be sure without
>> actually observing it, but I suspect that:
>> 1. The thermal mass is estracting heat, meaning cooler gases inside the
>> chamber, with risk of insufficient temperature for ignition at the top,
>> especially when nearing the end of pyrolysis.
>>
>> 2. Julien and Mahbubul can confirm about this: The concrete (or
>> ceramic) inner cylinder does not have any of the side holes (24 in the
>> metal version). Such holes allow for some "pilot light" effect after the
>> char level is below a hole. I imagine that small holes would be very
>> difficult to put into a concrete cylinder. However, maybe 3 or 6 holes
>> could be created at strategic locations (to be discussed). They could be
>> created in the following way:
>> When the concrete is being poured (or soon after), place something
>> like round toothpicks (about 2 mm size??) across the concrete, sticking out
>> both sides. (might be at a place in the mould with holes that would leak
>> concrete/water except that they would soon be "plugged" with the
>> toothpicks. When the piece is dried, and used for the first time (or two
>> or three times) the wood would burn out (or be drilled out or poked out),
>> leaving the desired hole.
>> Alternatively, do the same with larger diameter pieces like
>> chopsticks. If the holes are too large (to be determined by
>> experimentation), then they might be plugges slightly (in a variety of
>> ways.).
>>
>> First, let's get more understanding of the 24 "pilot light" holes in the
>> metal version.
>>
>> 3. How much supply of coconut shells (hard part) is there in your zone?
>>
>> Paul
>>
>> Doc / Dr TLUD / Prof. Paul S. Anderson, PhD
>> Email: psanders at ilstu.edu
>> Skype: paultlud Phone: +1-309-452-7072 <(309)%20452-7072>
>> Website: www.drtlud.com
>>
>> On 12/6/2017 11:55 PM, Ronal W. Larson wrote:
>>
>> Julien cc List
>>
>> Thanks for the answers below. Good to hear that both users with and
>> without land see value in making char. No new questions, two comments
>>
>> 1. Re a concrete inner cylinder, you said below “..*but their
>> smoke-free combustion was less reliable, and there were some gas burner
>> issues to solve. “*
>> It is not obvious to me why either concern should occur, so I hope
>> stovers everywhere could try this out. Seems likely to be cheaper (can
>> even maybe cast in place) and hopefully longer lived. We know usual cheap
>> steel has a limited life and the best steels are likely both not readily
>> available and expensive.
>> I forgot to congratulate on the two metal swinging “doors” at the
>> bottom. Nice solution.
>>
>> 2. Re fuels, the biochar list has had quite a lot of recent discussion
>> of “blue biochar” - where the source material is kelp or other seaweeds.
>> Bangladesh is possibly already in that business, because of its ocean
>> proximity. This could be a source of employment and a way to save forests
>> while having a feedstock that should bring back needed minerals and
>> fertilizer value. Beating the price of wooden blocks seems possible.
>>
>> Ron
>>
>> On Dec 6, 2017, at 10:05 PM, Julien Winter <winter.julien at gmail.com>
>> wrote:
>>
>> Hello all;
>>
>> Thanks for you comments on the Akha-Biochar Project in Bangladesh.
>>
>> The cost and payback is not fully worked out, because it will take about
>> a year for TLUD-biochar ecosystem to become established in community, and
>> it will continue to evolve. The stove costs about $20 to make, this could
>> be brought down as numbers of stoves increase. Also, we are still at the
>> stove-prototype stage, so we can expect some modifications and fine
>> tuning. Payback is developing, as farmers and gardeners discover the
>> value of biochar for food production. We have "Farmer Biochar User Groups"
>> that are conducting field trials, so they can learn from first-hand
>> experience what biochar can do for them. There are also graduate students
>> involved in gathering evidence to make recommendations on optimum
>> application rates. It could take a couple of years at any one location for
>> the local population to be able to place their own value on biochar, and
>> what they are willing to pay for it.
>>
>> Whether people use the char themselves or sell it depends on their
>> personal opportunities. There are many families that are landless.
>> Presently, they see char sales as a way to earn cash or barter. They think
>> that is a great idea; save fuel, cook faster, AND make biochar! People
>> with land, especially farmers, see biochar as a way of making permanent
>> improvements to the quality of their land, so expect that using biochar
>> could have very substantial impact on their family's economic well being.
>>
>> I have been advocating using biochar in composting, or mixing it with
>> manure before it goes onto the field. We need work on using it in human
>> waste management.
>>
>> There is no shortage of good soil scientists and agronomists in
>> Bangladesh to work on biochar technology.
>>
>> The outer concrete cylinder of the Akha stove is cast. We have made
>> stoves with concrete reactors (lined with clay slip), but their smoke-free
>> combustion was less reliable, and there were some gas burner issues to
>> solve. That is not to say that concrete reactors will not work, but they
>> need quite a bit of research and development, and a laboratory. Metal TLUD
>> reactors, on the other hand, are well understood. About 24 small holes in
>> the side wall of the metal reactor make the gasification of chunks of wood
>> more reliable, and less prone loosing the gas flame. We use cast concrete
>> (rather than clay) because it is easy to get concrete rings with flat
>> surfaces at the top and bottom. The concrete components are made
>> specifically for the Akha. There are many small business around who can
>> cast concrete.
>>
>> Mahbubul has been working with different ratios of Portand cement,
>> sawdust and biochar dust in the concrete. The more organics, the lower the
>> heat capacity and heat conductivity of the stove body. Micro porosity is
>> supposed to make concrete more resistant heat by providing spaces for
>> minerals to expand into. Obviously there is a trade-off between adding
>> organics and strength of the concrete. Different recipes are being tested
>> in the field. It is all trial and error.
>>
>> Mahbubul has also worked with local ceramic artisans to make the massive
>> stove components from clay. There very skilled people to work with, and
>> kaolinitic clay, so ceramic components are possible. The more metal
>> components on the stove that we can replace with ceramics the better,
>> because all metal in Bangladesh is imported.
>>
>> The Akha is about 25% more efficient than a traditional stove. The Akha
>> has gone through a water-boiling test at a laboratory in Dhaka, and was
>> about 30% efficient at getting energy from wood into the water. The main
>> view that the Akha saves 25% of the wood comes from household feedback.
>> That is what the women tell us.
>>
>> The Akha-Biocahr Project has funding for its current intervention until
>> 2019. It is enough to see if the TLUD-biochar technology will take root.
>> If it does, then the technology may spread all by itself as local
>> entrepreneurs see an opportunity. In fact, I think that if these
>> technologies viable, then they will out of our control and unstoppable.
>> The 'market' is 25 million homes. All the same, I am trying to raise money
>> so that Mahbubul and crew remain as proponents and stakeholders in what
>> they started. There is work to be done in developing compressed fuels,
>> because there is not enough wood in the country. We need to monitor the
>> impact on forest cover, and make sure that poorest households don't become
>> energy-starved if the price of wood goes up.
>>
>> One other thing that will push TLUD-biochar technology forward is that
>> sea-level rise could flood a third of the country, so soil productivity
>> needs to increase.
>>
>> Cheers,
>> Julien.
>>
>> --
>> Julien Winter
>> Cobourg, ON, CANADA
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